Anionic Phospho-Fries Rearrangement at Ferrocene: One-Pot Approach to P,O-Substituted Ferrocenes

For the first time the anionic phospho-Fries
rearrangement has
been successfully applied in ferrocene chemistry, giving access to
1,2-P,O-substituted ferrocenes. The 1,3 (O → C)-migration occurs
at ferrocenyl phosphates, thiophosphates, phosphite–borane
adducts, and phosphinates by treatment with a base such as lithium
diisopropylamide at low temperature, whereas the highest yields were
obtained starting from diethylferrocenyl phosphate. Complete reduction
of the phosphonate to a primary phosphine and subsequent Stelzer P,C
cross coupling allowed the synthesis of Fe­(η5-C5H3-2-OMe-PPh2)­(η5-C5H5) (1). The qualification of 1 as a supporting ligand in palladium-catalyzed Suzuki–Miyaura
C,C couplings has been proven by the synthesis of sterically congested
tri-ortho-substituted biaryls under mild reaction conditions in good
to excellent yields.